Flood Risk Management – Motorway Services


We have been working on flood risk and drainage aspects. The work was commissioned by Wardell Armstrong LLP (on behalf of Extra MSA Group) as part of a planning application to develop a Motorway Services Area (MSA) between Junctions 5 and 6 of the M42 in Solihull.

The challenge was to:

  • Confirm the flood risk
  • Classify the flood risk instead of relying on the Environment Agency’s Flood Zones
  • Set the heights of the proposed slip roads
  • Liaise with the LPA and peer review

All within an extremely tight timescales dictated by the planning calendar.


We built a river/floodplain/drainage model of the Shadow Brook and Aspbury’s Copse watercourses that cross the M42 in culvert. This incorporated the existing and proposed motorway works, consisting of:

  • Motorway drainage networks
  • Junction and slip roads
  • Extensions to the M42 culverts to accommodate the proposed slip roads

The model was subject to rigorous peer review and, despite programme constraints, was completed in time.


Our model compared the flood risk before and after the proposed MSA and enabled a number of stakeholders to remove their objections.  It also enabled the planning application to be submitted in time.

Contact us

For more information: Charles Mbigha

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